The cervix is basically just the neck of the uterus, and cramps can emanate from there, especially if the doctor didn't cut low down enough at the intersection of the cervix and uterus and left some uterine tissue.
Do you have endometriosis? If so, you unfortunately might be headed down the road I'm on, which is that a partial hyster leaves the cervix as a prime place for endo implants to grow. I still had periods and cramps every month, beyond the "mini period" that sometimes gets mentioned (had to use panty liners for five or six days each month).
I've already had to have a LEEP to core out my cervix, and I can feel it still didn't get all the endo, although I'm not bleeding anymore, at least. I'm probably going to have the cervix and my one remaining ovary removed.
But you are early in your recovery, so don't sweat some pains right now. It may take your body (and hormones) a little time to adjust from what just transpired....